Multi-omics insights into the molecular basis of powdery mildew resistance and root metabolic variation in Astragalus membranaceus var. mongholicus.

Powdery mildew is one of the major diseases affecting Astragalus membranaceus var. mongholicus (Bunge) P. K. Hsiao (Am), yet the molecular mechanisms underlying its defense response to this pathogen remain unclear. To identify candidate genes and differential biomarkers involved in resistance to powdery mildew, we used a highly resistant Am germplasm (202302006) selected from previous studies. After natural disease inoculation in the field, transcriptomic and metabolomic sequencing were performed. Differentially expressed genes (DEGs) and differentially accumulated metabolites (DAMs) in roots at various time points in response to powdery mildew were identified. Through DEG analysis, WGCNA, and LASSO regression, candidate genes and differentially abundant metabolites related to powdery mildew resistance were obtained. 6 upregulated candidate genes were enriched in pathways such as lipoic acid metabolism, sphingolipid metabolism, and carbon metabolism. 8 differential biomarkers were selected, with L-tartaric acid and ornithine identified as potential regulatory targets. Integrated omics analysis revealed significant enrichment of DEGs and DAMs in specific metabolic and biosynthetic pathways, with some metabolites showing positive/negative correlations with candidate genes, highlighting two key regulatory pathways. This study provides a comprehensive analysis of the mechanisms underlying the resistance of Am to powdery mildew, offering theoretical and technical support for the breeding of new powdery mildew-resistant cultivars.